CLAUDE_AX_SCREEN_READER=1 set correctly but screen reader mode doesn't activate (v2.1.237)

Description

Screen reader mode does not activate despite CLAUDE_AX_SCREEN_READER being correctly set to 1 in the shell environment before launching Claude Code. No [Screen Reader Mode: on via env] confirmation banner appears at startup, and the TUI renders normally (box-drawing chars, in-place redraws, arrow-key menus) instead of switching to flat linear text.

Environment

• Claude Code version: 2.1.237
• OS: Linux (kernel 7.0.11-76070011-generic)
• Terminal: GNOME Terminal
• Shell: bash

Steps to reproduce

1. export CLAUDE_AX_SCREEN_READER=1 in the shell
2. Start a new claude session from that shell
3. Observe startup output and TUI behavior

Expected behavior

Per docs (https://code.claude.com/docs/en/accessibility): first line printed should be [Screen Reader Mode: on via env], and the interface should render as plain labeled lines (you:, claude:, tool:, etc.) with numbered menus instead of arrow-key selection.

Actual behavior

No confirmation banner; normal TUI rendering (box characters, animated spinners, arrow-key menus) is used instead, as if the variable were unset.

Verification done

• Confirmed CLAUDE_AX_SCREEN_READER is present with value 1 in the process environment (checked via subprocess inherited env).
• Confirmed claude --version reports 2.1.237, well above the documented v2.1.181 minimum.
• Searched existing issues (CLAUDE_AX_SCREEN_READER, "screen reader mode") — found no existing report of this exact symptom (var confirmed set + version compatible, mode still not activating).